Download Ecology Review

SNC1D: BIOLOGY UNIT
Sustaining Ecosystems
Exam Review
Biodiversity
• the variety of organisms in an ecosystem
Biodiversity
Ecosystems with high biodiversity are more sustainable
because of redundancy in the food web.
If the number of
rabbits decreases,
the foxes can still
eat squirrels.
Biodiversity
Biodiversity will be higher in natural ecosystems than in
artificial ecosystems (e.g., a park).
Abiotic factor
• A non-living component of an ecosystem
Ex: sunlight, wind
Biotic factor
• A living component of an ecosystem
Ex: decomposers, predators
Limiting factor
• any factor (abiotic or biotic) that restricts the size of
a population
Ex. pH (acidity) in an aquatic ecosystem
Community
• all living things in an ecosystem
Population
• all individuals of the same species in the same
ecosystem
Carrying Capacity
• the maximum population size (of a particular
species) that an ecosystem can sustain
Ecological Niche
• the function of a species in its ecosystem
(what it eats, what eats it, how it behaves)
Trophic Level
• the position an
organism occupies in a
food chain
(the first or lowest trophic
level is Producers)
Producer
• an organism that makes
its own food
Consumer
• an organism that feeds
off other organisms
Decomposer
• an organism (e.g.,
bacteria, fungi) that
breaks down dead and
decaying organisms
(often not shown in food
webs)
Food Web
The greatest biomass/energy is found at the lowest
trophic level: the producers (here, the
phytoplankton).
Energy
Only about 10% of the energy is passed on to the next
level of the food chain; the remainder is used by the
organism for metabolism and growth.
Food Web: Effects
If the population of leopard seals declined, the
populations of its prey (e.g. fish) would increase and
the populations of its predators (e.g. smaller toothed
whales).
Cycling of Matter in Ecosystems
Carbon Cycle: the movement of carbon between the
lithosphere, atmosphere, hydrosphere, & biosphere
Cycling of Matter in Ecosystems
atmospheric pool of carbon dioxide
Cycling of Matter in Ecosystems
plants take up carbon
dioxide for photosynthesis
Cycling of Matter in Ecosystems
animals eat plants
Cycling of Matter in Ecosystems
carbon dioxide
released by
respiration
Cycling of Matter in Ecosystems
fossil fuels
Cycling of Matter in Ecosystems
carbon dioxide
released by
combustion
Cycling of Matter in Ecosystems
death of organisms
& decay by bacteria
2. Photosynthesis
• the chemical reaction that stores energy in nutrients
(in plants)
carbon dioxide + water → glucose + oxygen
4. Cell Respiration
• the chemical reaction that extracts energy from
nutrients (in plants and animals)
glucose + oxygen → carbon dioxide + water
Sustainable Farming
Soil-sustaining farming practices include no-tillage (to
reduce erosion) and drip irrigation (to reduce erosion
and leaching).
Habitat Fragmentation
• when wildlife areas are chopped up into
disconnected parts
Habitat Fragmentation
This is a bad thing because you need a large area for
large, stable populations.
To Improve Sustainability
One large block
is better than an
equal area of
smaller blocks.
To Improve Sustainability
The closer areas are to each other, the greater the
chance populations will be able to interact.
Wildlife corridors
connect areas and
further increase
the chance of
interaction.